Oscillator



April 25, 1949 c.. G. SMITH 2,468,127

l l oscILLAToR Filed Dec. 24, 1943 s sheets-sheet 1 44. ,CHARLES 675/107# April 26, 1949.

C. G. SMITH OSCILLATOR Filed Dec. 24, 1943 3 Sheets-Sheet 2 lllllllllz April 26, 1949. Q G SMITH 2,468,127

oscILLAToR Filed Dec. l:24, 1945 s snets-sheet s MAG/YE 7 /C FIELD CONTROL OSC/LL H T01? HTTX Patented Apr. 26, 1949 UNITED STATES PATENT OFFICE Raytheon Manufacturing Company, Newton, Mass., a corporation of Delaware Application December 24, 1943, Serial No. 515,57 7

(Cl. Z50-36) 11 Claims.

This invention relates to oscillators and more particularly to high frequency oscillators.

One of the objects of the present invention is to produce an oscillator in which practically the entire energy of the electron in flight is utilized.

Another object of the invention is to produce an oscillator in which the construction and arrangement are such that sharp pulsations of the grid voltage produce steady power pulsations in the induced oscillatory circuit.

Another object of the invention is to produce an oscillator in which electronic energy is coupled to an oscillating circuit by a magnetic couy pling.

Another object of the invention is to produce an oscillator in which electronic energy is coupled to the oscillatory circuit by a magnetic coupling and through an insulating medium.

A further obj ect of the invention is to produce a device in which very high frequency electric power can be fed advantageously through an insulating medium without overheating said medium.

These and such other aims and objects of the invention as may hereinafter appear will be readily understood from the following description, taken in connection with the accompanying drawing of one embodiment of the invention herein submitted for illustrative purposes.

In the drawing:

Fig. 1 is a horizontal cross-section on line I -I of Fig. 2 of one illustrative embodiment of the invention;

Fig. 2 is a vertical section on line 2--2 of Fig. 1;

Fig. 3 is a top plan view, partly in section, on line 3 3 of Fig. 2;

Fig. 4 is a bottom View, partly in section, on line 4-4 of Fig. 2;

Fig. 5 shows a modified output coupling;

Fig. 6 shows a broken partition for preventing electrostatic forces in the region of travel of the electrons;

Fig. 7 shows a circuit for a self-excited oscillator; and

Fig. 8 shows a circuit for an externally excited oscillator.

The illustrative embodiment of the invention shown in the drawing comprises an envelope 2 of any suitable material containing the electrode assembly including a cathode 4, a split anode, consisting of a plurality of transversely curved plates 6, and a grid 8 suitably mounted between said cathode and said anode plates. Herein said envelope 2 is made of glass and said cathode will preferably be cylindrical and contain a heater coil I0. The anode plates 6 are carried by electrically conductive rods I2 connected at top and bottom by circular conductors I4 and I6, (see Figs. 3 and4), and one longitudinal edge of each anode plate 6 extends adjacent and parallel to the grid 8, the grid members of which are similarly electrically connected at top and bottom by circular conductors I8, (see Figs. 2, 3 and 4). The upper and lower ends of said rods I2 engage holes in top and bottom spacing members 20 and 22, respectively, of mica or other suitable insulating material, said spacing members being provided about their perimeters with a plurality of suitably spaced resilient tooth-like members 24 adapted yieldingly to engage the inner wall of said envelope 2. Means are herein provided constituting an oscillatory circuit, said means herein illustratively comprising a cylindrical structure 26 of copper or other suitable electricallyconductive material herein illustratively surrounding said envelope 2 and comprising two semi-cylindrical portions connected by condenser plates 28.

The average potential of said structure 26 is substantially that of the anode plates 6.

In accordance with the present invention means may be provided in some cases to render the region in which the electrons travel substantially free from superposed electrostatic forces such, for example, as might be produced by bombardment of the inner wall of said envelope by electrons. Such means might illustratively comprise a coating or film of a high resistance substance, such as carbon, on the inner surface of said envelope, as shown at 30 in Fig. 4, or a broken partition of non-magnetic conductive material 3|, as shown in Fig. 6, near the inner surface of said envelope.

Referring to Fig. 4, the cathode heater coil I0 is connected to lead-in conductor 32 and conductor 34. Conductor 32 also supplies said cathode 4, and lead-in conductors 36 and 38 are joined, respectively, to lower circular conductor I8, connecting the grid members 8, and to the lower circular conductor I6, connecting the anode plates 6. A conductor 40 leads into said lm of carbon 30, (see Fig. 4), or to said broken partion 3|, as the case may be.

The invention contemplates the use of any suitable means for producing a moderate magnetic field substantially parallel to said cathode 4 within the apparatus. Said means herein illustratively comprises magnet pole pieces 42 and 44, suitably located one above and the other'below said envelope 2, (see Fig. 2). In some cases it may be desirable to make the eld very slightly concave on the side toward the cathode, but the departure of said eld from parallelism with the cathode is so very slight that substantial parallelism exists.

The high frequency energy developed by the apparatus is conveniently coupled directly to the output by any suitable means. In Figs. 1, 7 and 8 is shown a convenient coupling comprising a loop 45 magnetically coupled to the oscillating current and having one end connected to said oscillatory circuit 26 and the other to a rod 49 coaxial with a tubular wave guide 41 connected to the oscillatory circuit 26.

In Fig. is shown a modied coupling for this purpose, which comprises tubular wave guide 5|, connected by a conductor 53 to one of the condenser plates of condenser 2B, and a rod 55 coaxial with said wave guide, connected by a conductor 51 to the other plate of condenser 28. The liig'h frequency energy will thus be directly coupled tothe output.

If the electrons are emitted in sharp pulsations from said cathode with proper frequency, the resultant electron current will induce oscillations in the oscillatory circuit comprising said cylindrical structure 25, and it will be apparent that the longer the flight of the electrons, the longer will be their inductive action upon said oscillatory circuit and the stronger will be the oscillatory current induced in said circuit. The grid 8 provides a convenient means for securing such sharp pulses of electron emission. The cathode 4 is adapted to emit electrons continu- -ously. Thus when no electron emission into the space beyond the grid is desired, a suitable negative voltage on the grid will prevent such electron emission. When a pulse oi electrons is desired, the grid 8 is driven more positive by a ysuitable control voltage, and under these conditions the desired pulse of electro-ns will be emitted into the space beyond the grid. As pointed out above, to produce the oscillations it is necessary only that the electrons be emitted in sharp pulses. The period during which the grid permits elec- `vt'rons to pass through it, therefore only need be a small fraction of a half cycle of the oscillations produced in the outer oscillating circut.

The magnetic iield created by said pole pieces 42 'and 44 is availed of to divert the individual electrons of the electron stream emanating from the cathode 4 from their normal courses and to yconstrain them to follow curvilinear paths, subvstantially as indicated by dotted lines in Fig. l. These individual curvilinear paths together form in effect a circulatory current of electrons within Irsaid envelope and the electrons in this current will thus travel longer paths than they normally `would. In addition to this increase in the oscillatory current due to the prolongation of the Yflight of the electrons by the action of said magnetic field, their night is still further prolonged -owing to the fact that the -oscillatory current induced in said oscillatory circuit, as it reacts yupon said electron current by electro-magnetic induction, tends to retard their flight, thus still Afurther prolonging their inductive action.

In accordance with the present invention the relative adjustment oi the magnetic iield and the Avoltage applied between the cathode and anode 'Will-preferably be such that the time of travel of ran electron will substantially equal the time itheanod'e itwill have given up practically all its A energy for the induction of said oscillatory current. Also with such an adjustment, the sharp, square wave impulses upon the grid, While they produce sharp impulses of electron current, that is to say at a predetermined frequency and lasting only during a minor portion of a half cycle of the oscillatory circuit, cause only steady, approximately sinusoidal impulses throughout substantially a whole half cycle of said oscillaatcry current. These factors make practicable the production of oscillatory power without a great amount ci energy going into harmonics of the desired frequency, and add greatly to the efficiency and output of the apparatus and therefore to the practical value of the present invention. Wave lengths of the order of one meter are readily produced, so that single tubes of very large capacity appear possible by the use of applicants invention.

The electronic space charge is equal to the plus charges on the anode plates and on other elements oi the structure surrounding the electronic orbits. rThese can be made very large and therefore the electron current can be large. It follows that the present invention should make possible the production of oscillators oi very great power and efficiency.

It will be noted that the present invention couples the eiectronic energy to radiation by the magnetic field created by the electrons in iiight. This is a distinct advantage as it does away with certain objectionable features incidental to electrostatic couplings, such, for example, as heavy stresses and consequent dielectric losses. It will also be noted that the magnetic coupling can be eiected through glass, without overheating the glass. Applicants invention therefore teaches that very high frequency electric power can be fed advantageously through an insulating medium without overheating said medium. This is due chiefly to the absence of the heavy stresses above referred to.

From the above disciosure it would appear that the present tube is especially adapted to eicient generation of power over a considerable range of frequencies. It can be readily made in large sizes.

For some purposes the grid structure may be electrically connected to the anode plates through loops 53. Such a connection is shown in Figs. 3 and 7. Voltages induced magnetically in these loops swing the grid through a desired voltage variation.

Fig. 7 shows an illustrative circuit for a selfexcited oscillator embodying the present invention. The parts are shown only diagrammatically. A suitable source of voltage, a battery 33, for example, has its negative pole directly connected to the cathode l by conductor 39, and its positive pole Si connected to the anode plates t through the conductor 4l and circular 'conductor l@ connecting said plates. 'The anode plates are connected to the grid members 8 .by the above-mentioned loops 4B. As above stated, voltages induced magnetically in these loops swing the grid through a desired voltage variation. A suitable controlling or restraining resistance 43 will preferably be inserted in the circuit.

Fig. 8 shows an illustrative circuit for an externally-eXcited oscillator embodying the present invention. In this circuit the loops 48, connecting the grid members to the anode `plates Vtor swinging the grid through the desired voltage variation by the voltages magnetically induced therein, are omitted and an external control ches-,127"

oscillator, diagrammatically shown at 45, is substituted for that purpose. A suitable source of voltage, a battery 41, for example, has its negative pole 49 connected to the cathode l by conductor 50 and to the grid member by conductor h2 through said control oscillator 45. rI'he positive pole 54 of said battery is connected to the anode plates 6 by conductor 56 and the circular conductor I6 connecting said anodes. Said conductor 56 Will preferably contain a controlling or restraining resistance 58.

In both Fig. 7 and Fig. 8 the grid members are interconnected by the circular conductor it and the anode plates 6 are interconnected by the cirn cular conductor i6. The cylindrical structure 25 herein illustratively forming the oscillatory circuit comprising condenser plates 28 surrounds the envelope 2 containing the electrode assembly and is provided with a coupling for coupling the high frequency energy developed by the apparatus directly to the output. This coupling may be the same as that shown in Fig. 1 and comprises a loop 45 magnetically coupled to the electron current and having one end connected to the oscillatory circuit 26 at 59 and its other end connected to a conductor rod i9 coaxial with the tubular wave guide 41, coaXially surrounding said rod lil and connected to said oscillatory circuit 26. A lead 60 connects the lm 36 to the conductor 4l through a small battery 6 i. The broken partition 3|, shown at Fig. 6, may be similarly connected.

Wherever the word plurality occurs in the specication and claims, said Word is to be understood as meaning two or more.

I am aware that the present invention can be restrictive, reference being had to the appended claims rather than to the aforesaid description to indicate the scope of the invention.

What is claimed is:

1. The combination of a cathode adapted to emit electrons, a series of anode elements positioned circularly of said cathode, and means comu prising a grid between said cathode and said anode elements to cause the electrons emitted by said cathode to flow toward said anode elements in pulsations, means for creating a magnetic parallel to said cathode for diver-tin trons emitted from said cathode fron t tilinear paths and causing them to a cirM culatory stream and create a magnetic field substantially parallel with the axis of flow of said 'circulatory stream, and an oscillatory circuit magnetically coupled to said magnetic eld cre ated by said circulatory stream, to transfer energy from said electron stream to said oscillatory circuit.

2. In an electric oscillator, the combination of an envelope containinga cathode adapted to emit electrons, an anode assembly comprising a series of anode elements around said cathode, and a grid between said cathode and said anode assembly, means comprising said grid to cause the electrons emitted by said cathode to flow toward said anode assembly in pulsations, means to maintain a magnetic eld within said envelope substantially parallel to said cathode for diverting the electrons emitted by said cathode from normal rectilinear paths and causing them to flow in a circulatory stream and create a magnetic field substantially parallel with the axis of flow of said circulatory stream, an oscillatory circuit magnetically coupled to said magnetic iield thus created, to transfer energy from said electron stream to said oscillatory circuit, and means for rendering the regions in which the electrons travel free from superposed electrostatic forces.

3. In an electric oscillator, the combination of an envelope containing a cathode adapted to emit electrons, an anode assembly comprising a series' normal rectilinear paths and causing them to` flow in a circulatory stream and create a magnetic eld substantially parallel with the axis of flow of said circulatory stream, an oscillatory circuit magnetically coupled to said magnetic eld thus created, to transfer energy from said electron stream to said oscillatory circuit, and a high,

resistance coating upon the inner surface of said envelope to render the regions in Which the electrons travel substantially free from superposed.

electrostatic forces.

4. In an electric oscillator, the combination of an envelope containing a cathode adapted to emit electrons, an anode assembly comprising a series of anode elements around said cathode, and a gridY between said cathode and said anode assembly, means comprising said grid to cause the electrons emitted by said cathode to now toward said anode assembly in pulsations, means for maintaining a magnetic field within said envelope substantially parallel to said cathode for diverting the elec? trons emitted by said cathode from normal rectilinear paths and causing them to flow in a circulatory stream and create a magnetic eld substantially parallel with the axis of the flow of said circulatory stream, an oscillatory circuit magnetically coupled to said magnetic field thus created, to transfer energy from said electron stream to said oscillatory circuit, and a broken partition of non-magnetic conductive material adjacent the inner surface of said envelope to prevent bombardment of said surface by electrons.

5. In an electric oscillator, the combination of an envelope containing a cathode adapted to emit electrons, an anode assembly comprising a series of transversely curved anode elements suitably spaced around said cathode, and a grid between said cathode and said anode assembly, means comprising said grid to cause the electrons emitted from said cathode to flow toward said anode elements in pulsations, means for maintaining a magnetic field within said envelope substantially parallel to said cathode for diverting the electrons emitted by said cathode from normal rectilinear paths and causing them to flow in a circulatory stream and create a magnetic eld substantially parallel with the axis of flow of said circulatory stream, and an oscillatory circuit magnetically coupled to said magnetic ield thus created, to transfer energy from said electron stream to said oscillatory circuit.

6. In an electric oscillator, the combination of an envelope containing a cathode adapted to emit electrons, an anode assembly comprising a series of anode elements all transversely curved in the same direction and suitably spaced around said cathode, and a grid between said cathode and said anode assembly, means comprising said grid to 7 cause the electrons emitted by sai'dl cathode to flow. toward said anode elements in pulsations,

means for maintaining a magnetic field within` create a magnetic field substantially parallel with` the axis of flow of said circulatory stream, and an oscillatory circuit magnetically coupled to said magnetic field thus created, to transfer energy from said electron stream to said oscillatory circuit 7. In an electric oscillator, the combination of an envelope containing a cathode adapted to emit electrons, an anode assembly comprising a series o'flanode elements suitably spaced around said cathode, and a grid between said cathode and s aid anode assembly, means comprising said grid to cause the electrons emitted by said cathode to flow toward said anode elements in pulsations, means lfor maintaining a magnetic ield within said envelope substantially parallel to said cathodefor diverting the electrons emitted by said cathode from normal rectilinear paths and causing them to flow in a circulatory stream and create a magnetic neld substantially parallel with the axis of flow of said circulatory stream, said anode elements being all transversely curved in the general direction of flow of said circulatory stream, and an oscillatory circuit magnetically coupled to said magnetic field thus created, to transfer energy from said electron stream to said oscillatory circuit.

8. rThe combination of a cathode adapted to emit electrons, an anode assembly adjacent said cathode, means to cause the electrons emitted by said cathode to flow toward said anode assembly in pulsations, means for diverting the electrons emitted by saidy cathode from normaly rectilinear paths and causing them to ow in la circulatory streamfand create a magnetic leld substantially parallel with the axis of flow of said circulatory stream, an insulating medium, and an oscillatory circuit magnetically ycoupled to said magnetic field through said insulating medium, to transfer energy from said electron stream tol said oscillatory circuit through said insulating medium.

9. The combination of a cathode adapted to emit electrons, an anode assembly comprising a series of transversely curved anode elements suitably spaced around said cathode, ineans to cause the electrons emitted by said cathode to now toward said anode elements in pulsations, moans for diverting the electrons emitted by said cathode from normal rectilinear paths and causing them to flow in a circulatory stream andl create a magnetic field substantially parallel With the axis of flow of said circulatory stream, and an` oscillatoryl circuit magnetically coupled to said magnetic eld thus created, to transfer energyfrom said electron stream to said oscillatory circuit.

10. The combination of a cathode adapted to emit electrons, an anode assembly comprising a series of anode elements suitably spaced around said cathode and transversely curved in the same direction, means to cause the electrons, emittedA from said cathode to flow toward, said anodel elements in pulsations, means for diverting the electrons emitted by said cathode from normal rectilinear paths and causing them to flow in a circulatory stream and create a magnetic fieldA sub, stantially parallel with the axis of thel flow of said circulatory stream, and an oscillatory circuit magnetically coupled to said magnetic field thus created, to transfer energy from said electron stream to said oscillatory circuit.

11. The combination of a cathode adapted to emit electrons, an anodeassembly comprising a .series of anode elements suitably spaced: around said cathode, means to cause the electrons emittedv by said cathode to flow toward said anode ele. ments in pulsations, means for diverting the elec-r trons emitted by said cathode from normal rec-k tilinear paths and causing themto flow in acircu-.,

latory stream and create ay magnetic; eldsubstantially parallel with the axis of ow of said circulatory stream, said anode elements being all curved in the direction of flow of said stream, and an oscillatory circuit magnetically coupled to said magnetic field created by said circulatory stream, to transfer energy from said electron stream to said oscillatory circuit.

The following references are. of record inthe file of this patent:

UNITED STATES PATENTS Number Name Date 1,219,961 Langmuir ,Man 20, 1917 2,093,683 Lindenblad Sept. 21,I 1937 2,099,533 Prinz NOV. 16, 1937 2,163,756 Llewellyn June 27, 1939 2,178,056 Taylor Oct. 31, 1939 2,196,392 Hansell Apr. 9, 1940 2,233,263 Linder Feb, 25, 1941v 2,250,511 Varian July 29, 1941 2,256,608 Braden Sept. 23, 1941` 2,259,690 Hansen Oct, 21, 1941 2,264,858 Record Dec. 2, 1,941 2,272,165 Varian Feb. 3, 1 942 2,281,935 Hansen MayA 5, 1942 2,289,319 Strobel July 7, 1942 2,342,263 Fremlin Feb. 22, 1944v 

